B738 manual speed brake landing
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B738 manual speed brake landing
There is an amber light for this leading you to a QRH. There is no mention of any landing penalty. There is no data in NNC landing distance requirements. Thus there would appear to be no adjustment necessary to landing distance calculations. However, I've heard of a company imposing an adjustment whereby you assume an increased landing weight thus increasing the landing distance required. Does anyone know if this is a Boeing or that company's SOP. If it is Boeing why is there no mention in the QRH?
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1) (All Models except -800 with Short Field Performance (SFP) Option and -900ER)
(M)(O) May be inoperative provided:
a) System is deactivated,
b) Operations are conducted in accordance with AFM, and
c) For models with Blended Winglet with Speed Brake Load Alleviation System, Speed Brake Load Alleviation System is considered inoperative.
2) (-800SFP and -900ER)
(M)(O) May be inoperative provided:
a) System is deactivated,
b) Appropriate performance adjustments are applied, and
c) For models with Blended Winglet with Speed Brake Load Alleviation System, Speed Brake Load Alleviation System is considered inoperative.
Did you check your MEL, this is the MMEL. They may have replaced the "Appropriate performance adjustments are applied" with more detail.
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(M)(O) May be inoperative provided:
a) System is deactivated,
b) Operations are conducted in accordance with AFM, and
c) For models with Blended Winglet with Speed Brake Load Alleviation System, Speed Brake Load Alleviation System is considered inoperative.
2) (-800SFP and -900ER)
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(M)(O) May be inoperative provided:
a) System is deactivated,
b) Appropriate performance adjustments are applied, and
c) For models with Blended Winglet with Speed Brake Load Alleviation System, Speed Brake Load Alleviation System is considered inoperative.
Did you check your MEL, this is the MMEL. They may have replaced the "Appropriate performance adjustments are applied" with more detail.
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Performance penalty:
The reason behind this is the following. For B737 with SFP installed the auto speedbrake system operates the speedbrakes at an higher angle than you would manually operate the speedbrakes. For the other models the angle is the same for auto & manual operation. That's why you need a performance penalty (ASDR & LDR) on SFP 737's & not on other models.
The performance penalty is the following (from B737 DDG):
Why there is no mention of it in the QRH is a good question. There is a small note saying you need to add 50 meters when using manual speedbrakes but it's the same for SFP & non-SFP.
The reason behind this is the following. For B737 with SFP installed the auto speedbrake system operates the speedbrakes at an higher angle than you would manually operate the speedbrakes. For the other models the angle is the same for auto & manual operation. That's why you need a performance penalty (ASDR & LDR) on SFP 737's & not on other models.
The performance penalty is the following (from B737 DDG):
3. Reduce performance limited weights by the following:
For 737-800SFP:
A. Takeoff field length limit weight and brake energy limit weight: 2300
lb (1044 kg)
B. Landing field length limit weight: 13,000 lb (5897 kg)lb (1044 kg)
For 737-900ER:
A. Takeoff field length limit weight and brake energy limit weight: 1600
lb (726 kg)
B. Landing field length limit weight: 15,000 lb (6804kg)lb (726 kg)
Why there is no mention of it in the QRH is a good question. There is a small note saying you need to add 50 meters when using manual speedbrakes but it's the same for SFP & non-SFP.
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That's exactly my point: there is an amber light; you consult the QRH, it tells you nothing and YET there is a landing penalty and there's nothing in the NNC landing tables. Most bizzare.
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There is something in the normal configuration landing distance tables in my QRH, it mentions that the data for max manual braking is only valid for auto speed brakes, for max manual braking and manual speed brakes you have to add 55m in the non-SFP versions and 65m (F30) or 60m (F40) in the SFP version.
The MEL at least tells us right away to add the performance penalty shown by our landing performance program on the EFB and additionally to check the DDG for an inflight penalty (for planes with load alleviation the speed might be limited to 265kias inflight). However, nothing in the QRH, except a full non-normal descent, approach and landing checklist.
The MEL at least tells us right away to add the performance penalty shown by our landing performance program on the EFB and additionally to check the DDG for an inflight penalty (for planes with load alleviation the speed might be limited to 265kias inflight). However, nothing in the QRH, except a full non-normal descent, approach and landing checklist.
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There is something in the normal configuration landing distance tables in my QRH
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The amber light leads you to a two page non normal checklist. Nothing i would do on the run during an approach, so a missed approach and sorting it out in the hold is probably the best thing to do, and since it could lead to a changed landing performance it is best practice to re-calculate the landing distance, which would lead me to a performance penalty direct from our EFB program.
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I have had this several times. If you have seen it before, it's hardly worth making a go around for that.
The checklist is effectively one item "Do not arm the speed brake for landing, manually deploy speedbrake immediate upon landing".
That's it.
The checklist is effectively one item "Do not arm the speed brake for landing, manually deploy speedbrake immediate upon landing".
That's it.
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Actually, its two different checklists depending on tab number, and it says a bit more, some stuff about speed limits and such, and then there is the issue of a nearly 6t performance correction. During approach i haven't seen it yet for more than a second, which indeed doesn't really justify a go around. A steady amber light however is probably an indicative of something else.
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There are lot of assumptions here. I don't think we are at the same page (metaphorically! Not page in QRH. Oh the joy of the written language. 
Are we in-flight or doing pre-flight? Let's not confuse MEL items with QRH.
My comment was aimed at the situation, when you on approach arms the speed brake and the amber "speed brake do not arm" light illuminates.
In this scenario, my comment was that it's not worth doing a go around, since the only thing the checklist will tell you to do is to use the speed brakes manually.
There are no speed limits for a "speed brake do not arm" light, that illuminates on approach (flaps not up) when attempting to arm the speed brakes.
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If, on the other hand, it illuminated during cruise or descend (in which case you have plenty of time to deal with it), the only restriction that applies in flight is for winglet models, with max speed of 320 knots. You may still attempt to arm the speed brakes for landing. This scenario will only occur on winglet models, since it's only for winglet models that the "speed brake do not arm light" has this additional warning function.
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If you have the problem on ground of course it's a different matter. And should be dealt with accordingly (MEL/DDG). And correctly as you say there are more restrictions for the winglet models. Here the load alleviating system is assumed completely INOP along with the auto speed brake system. And correctly there are some limits on airspeed and MTOW.
But these restrictions are a result of the failed Load Alleviating System and not the auto speed brake.
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As an answer to the original poster, neither the QRH, MEL or DDG of my company imposes any restrictions on landing distance with a failed speed brake. And why should there be?
At any landing it is assumed that the auto speed brake system might fail, and hence the Pilot Monitoring is vigilantly ready to manually raise the speed brake. When it actually is not armed, we even eliminated the element of surprise, so I don't see any reason why the PM should not be able to raise it as fast as the auto system.
Are we in-flight or doing pre-flight? Let's not confuse MEL items with QRH.
My comment was aimed at the situation, when you on approach arms the speed brake and the amber "speed brake do not arm" light illuminates.
In this scenario, my comment was that it's not worth doing a go around, since the only thing the checklist will tell you to do is to use the speed brakes manually.
There are no speed limits for a "speed brake do not arm" light, that illuminates on approach (flaps not up) when attempting to arm the speed brakes.
---
If, on the other hand, it illuminated during cruise or descend (in which case you have plenty of time to deal with it), the only restriction that applies in flight is for winglet models, with max speed of 320 knots. You may still attempt to arm the speed brakes for landing. This scenario will only occur on winglet models, since it's only for winglet models that the "speed brake do not arm light" has this additional warning function.
---
If you have the problem on ground of course it's a different matter. And should be dealt with accordingly (MEL/DDG). And correctly as you say there are more restrictions for the winglet models. Here the load alleviating system is assumed completely INOP along with the auto speed brake system. And correctly there are some limits on airspeed and MTOW.
But these restrictions are a result of the failed Load Alleviating System and not the auto speed brake.
---
As an answer to the original poster, neither the QRH, MEL or DDG of my company imposes any restrictions on landing distance with a failed speed brake. And why should there be?
At any landing it is assumed that the auto speed brake system might fail, and hence the Pilot Monitoring is vigilantly ready to manually raise the speed brake. When it actually is not armed, we even eliminated the element of surprise, so I don't see any reason why the PM should not be able to raise it as fast as the auto system.
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I take it you do not operate the -800SFP or the -900ER then? Both have landing performance limitations which have to be taken into account. 13000 lbs for the -800 is quite a bit actually and can alter your landing performance significantly. It is in the MMEL which should be part of your MEL.
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Still, the performance penalty for the SFP models is technically only a dispatch concern, I say technically because obviously the prudent pilot should either know about the extra 'oomph' the spoilers have on the SFP and the increase in braking performance they give if deployed automatically during landing or should have a quick glance at the MEL and reevaluate the conditions. Unless the landing is critical I still wouldn't go around if the light comes on on final.
